timestamp converter

Timestamp Converter

Convert Unix epoch (seconds or milliseconds) to and from a human-readable date, ISO 8601, and a read-only world-clock view across common timezones.

Runs fully in your browser · nothing is sent anywhere

Notes

Epoch unit is auto-detected from magnitude (10-digit values are treated as seconds, 13-digit as milliseconds) — override with the Seconds/Milliseconds toggle if you have an unusual value.
The local date/time field is interpreted in this browser's timezone. Converting a wall-clock time in a specific named timezone (e.g. "3pm in Tokyo, what's the epoch?") isn't supported yet — the world clock below shows the reverse direction (a given instant, viewed in other timezones) correctly, since that's unambiguous.
All timezone math is delegated to the browser's built-in Intl API, which already knows every timezone's current DST rules — nothing here is manually computed.
"Relative" time (e.g. "3 hours ago") uses Intl.RelativeTimeFormat and is relative to the moment you last converted, not a live-updating clock.